1. Field of the Invention
The present invention relates to a recording and/or reproducing apparatus and method using a key frame, and more particularly, to an apparatus and method for recording and/or reproducing a moving picture using key frames by which the overall scenario of moving picture contents can be ascertained during a trick-play mode.
2. Description of the Related Art
In related art moving picture recording method, moving picture data streams are recorded on a recording medium as they are, and in existing moving picture reproduction methods, the recorded moving picture data streams are reproduced at a normal speed or at a higher speed according to a given reproduction speed factor. During a normal speed reproduction mode, reproduction is performed at a normal speed. During a high-speed reproduction mode, reproduction is performed at a speed of 2 times, 4 times or 6 times the normal speed.
While conventional moving picture reproduction methods are performed at a fixed speed selected from predetermined reproduction speed factors, the same situation is encountered during a high-speed reproduction mode, such as a trick-play mode. In other words, in a trick-play mode, reproduction is performed at a speed selected from 2 times normal speed, 4 times normal speed or 6 times normal speed.
However, the aforementioned related art has various problems and disadvantages. For example, but not by way of limitation, it is difficult to reproduce only the key frame corresponding to a user""s desired representative picture when using the conventional moving picture reproduction method. Accordingly, it is quite difficult for a user to accurately detect and reproduce a desired scene (e.g., the title of a movie) from moving pictures reproduced at a high speed, like in a trick-play mode.
To overcome the above-described problem, there has been proposed a related art method in which, while watching moving picture contents, a user directly marks every desired scene to be reproduced and the marked scenes are used as key frames during reproduction. However, according to this related art method, the user must mark every desired scene manually while watching moving picture contents. As marking is done manually, it is not easy to accurately mark only key frames representing the overall scenario of moving pictures occurring in real-time. Further, the related art does not provide for automatic marking of the key frames.
To solve the above problems, it is a feature of the present invention to provide a recording apparatus for automatically determining positions of representative contents by which the overall scenario can be estimated, from input data streams.
It is another feature of the present invention to provide a reproducing apparatus for automatically searching for the position of a representative content recorded by the recording apparatus and reproducing the same.
It is still another feature of the present invention to provide a moving picture recording apparatus for automatically determining positions of representative contents by which the overall scenario can be estimated, from input moving picture data streams.
It is a further feature of the present invention to provide a moving picture reproducing apparatus for automatically searching for the position of a representative content recorded by the moving picture recording apparatus and reproducing the same.
It is a another feature of the present invention to provide a moving picture recording and/or reproducing method of automatically recording the position of a representative picture by which the overall scenario can be estimated from input moving picture data streams, and reproducing only the recorded representative picture.
In an aspect of the present invention, there is provided a recording apparatus including input means for inputting coded data streams, a recording medium on which data streams are recorded, and recording means for detecting representative contents when it is determined that there is a change in contents of the coded data streams, and recording the input coded data streams on the recording medium while marking the position of the detected representative contents, the change in contents being determined based on distribution characteristics of macro blocks of frame units for the input coded data streams.
The recording means preferably detects a subsequent intra frame after it is determined that there is a change in contents, as representative contents.
In another aspect of the present invention, there is provided a moving picture recording apparatus including input means for inputting coded data streams, a recording medium, and recording means for detecting a representative picture when it is determined that there is a scene change of the coded moving picture data streams, and recording the input coded moving picture data streams on the recording medium while marking the position of the detected representative picture, the scene change being determined based on distribution characteristics of macro blocks of frame units for the input coded moving picture data streams.
The recording means preferably includes a key frame detection and mark unit for detecting the position of a key frame corresponding to the representative picture among the moving picture data streams and marking the position thereof, and a recording processor for recording the moving picture data stream having the representative picture position marked therein on the recording medium.
The key frame detection and mark unit preferably detects a subsequent intra frame after it is determined that there is a scene change, as the key frame, the key frame detection and mark unit preferably determines that there is a scene change when the distribution degree of the intra macro blocks of the frame unit is out of a normal tolerance in view of a sequence of frames compatible with coding standards of the coded moving picture data streams.
The position data of the representative picture is preferably recorded either separately from or together with the coded moving picture data streams.
In another aspect of the present invention, there is provided a reproducing apparatus including a recording medium having coded data streams and position data of representative contents detected according to a change in contents of the coded data streams, recorded thereon, the position of the representative contents being determined based on distribution characteristics of macro blocks of frame units of the coded data streams, and reproducing means for searching for the position data of representative contents recorded on the recording medium and reproducing the representative contents.
In a further aspect of the present invention, there is provided a moving picture reproducing apparatus including a recording medium having coded moving picture data streams and position data of a representative picture detected when there is a scene change of the coded moving picture data streams, recorded thereon, the position of the representative picture being determined based on distribution characteristics of macro blocks of frame units of the coded moving picture data streams, and reproducing means for searching for the position data of a representative picture recorded on the recording medium and reproducing the representative picture.
The reproducing means includes a key frame position search unit for searching for the position data of the key frame corresponding to the representative picture among the moving picture data streams recorded on the recording medium, and a reproduction processor for reading out the moving picture data steam corresponding to the key frame while skipping all unmarked frames between key frames, by using the key frame position data found by the key frame position search unit, and restoring the read data stream into uncoded original picture data. The key frame is preferably an intra frame generated after the scene change occurs.
In another aspect of the present invention, there is provided a recording method including the steps of (a) if coded data streams are applied, detecting whether there is a change in contents based on distribution characteristics of macro blocks of frame units, (b) detecting a subsequent intra frame after it is determined that there is a change in contents, as representative contents, (c) marking the position of the detected representative contents, and (d) recording the coded data streams marked with the position of the detected representative contents.
The step of detecting whether there is a change in contents is preferably performed based on distribution characteristics of intra (I) macro blocks of frame units and the sequence of frames.
In still another aspect of the present invention, there is provided a moving picture recording method including the steps of (a) if coded moving picture data streams are applied, detecting whether there is a scene change based on the sequence of frames based on coding standards and the distribution degree of macro blocks of frame units, (b) if there is a scene change, detecting a subsequent intra frame after it is detected that there is a scene change, as a representative picture, (c) marking the position of the detected representative picture, and (d) recording the coded moving picture data streams marked with the position of the detected representative pictures.
In step (a), if the coding standards are MPEG standards, the frames of the coded moving picture data streams are divided into I frames, B frames and P frames and the scene change is preferably detected based on distribution characteristics of intra macro blocks in units of frames.
In still another aspect of the present invention, there is provided a reproducing method for reproducing data from a recording medium having coded data streams marked with the positions of representative contents, from which a scenario can be estimated, the method including the steps of (a) if a trick-play mode is set, searching for the position data of the representative contents recorded on the recording medium, (b) while controlling the reproduction position of the recording medium based on the position data of the representative contents found in step (a), reading the data stream recorded on the recording medium, and (c) restoring the data stream read in step (b) into uncoded original picture data.
According to a further aspect of the present invention, there is provided a moving picture reproducing method for reproducing a moving picture from a recording medium on which coded moving picture data streams having a representative picture position marked therein according to a scene change are recorded, the method including the steps of (a) if a trick-play mode is set, searching for the representative picture position recorded on the recording medium, (b) while controlling the reproduction position of the recording medium based on the position data of the representative picture found in the step (a), reading the moving picture data stream recorded on the recording medium, and (c) restoring the moving picture data stream read in step (b) into uncoded original picture data.
The moving picture reproducing method may further include the step of displaying the uncoded original picture data at a high speed, or displaying the uncoded original picture data at a normal speed.